


Additions

by Accidental_Ducky



Series: Sparks and Lightening [2]
Category: Teen Wolf (TV), The Mortal Instruments Series - Cassandra Clare
Genre: Derek's an uncle, F/M, Jem is still a badass, M/M, Mermaids, Peter's still a little shit, Well that's the title he claims anyway, shadowhunters au
Language: English
Status: Completed
Published: 2018-02-26
Updated: 2018-02-26
Packaged: 2019-03-24 05:05:15
Rating: Teen And Up Audiences
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 2,776
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/13804014
Author URL: https://archiveofourown.org/users/Accidental_Ducky/pseuds/Accidental_Ducky
Summary: Derek had never been the Clave’s biggest fan considering the way they treated Downworlders as second-class citizens, but seeing Jem Carstairs holding a feral omega against the brick wall of Sparks and Lightening was making him reevaluate that a bit. It had been hard work to track the omega down in the first place and Derek had been caught off guard when it cornered him in an alley, but then Jem had come charging in like Death in designer jeans.“Holy fuck,” the werewolf breathes in shock, watching muscles shift under the pale skin of Jem’s arm—he always forgot how strong this Shadowhunter (Silent Brother?) was until he was given a demonstration. “Where’d you come from?”“Does that really matter,” Jem asks, looking over at him with a quirked brow. “I believe I’ve just saved you from being gutted outside your Uncle’s bookshop.”“Yeah, thanks for that.”





	Additions

Derek had never been the Clave’s biggest fan considering the way they treated Downworlders as second-class citizens, but seeing Jem Carstairs holding a feral omega against the brick wall of _Sparks and Lightening_ was making him reevaluate that a bit. It had been hard work to track the omega down in the first place and Derek had been caught off guard when it cornered him in an alley, but then Jem had come charging in like Death in designer jeans.

“Holy fuck,” the werewolf breathes in shock, watching muscles shift under the pale skin of Jem’s arm—he always forgot how strong this Shadowhunter (Silent Brother?) was until he was given a demonstration. “Where’d you come from?”

“Does that really matter,” Jem asks, looking over at him with a quirked brow. “I believe I’ve just saved you from being gutted outside your Uncle’s bookshop.”

“Yeah, thanks for that.” The omega lets out a snarl that had the ‘wolf’s attention sliding back to it as it struggled against Jem’s hold. Derek knew from experience that having anyone near your throat was an uncomfortable situation, but having the hold being as tight as Jem’s or belonging to a stranger, then it bordered on threatening. Especially when the person holding was, you know, ripped.

“Now, would you like to ask him some questions or was there another reason you had for tracking him down?” Derek tightened his jaw as he stood up, thanking all the gods in heaven that Stiles and Peter were determined to keep even their alley clean so that he didn’t have slime and muck covering his back from where he’d been thrown.

“What’s your name?” The omega snaps at him, fangs clicking together almost violently, eyes blazing Beta gold. _At least he hasn’t killed anyone yet_. Derek allows his eyes to bleed red and puts as much command in his voice as he’s able when he repeats his question.

“Javier,” he grits out, struggling against Jem’s hold. The Shadowhunter didn’t appear worried, but Derek had heard stories about this one. This was the man that had been tortured by a Greater Demon, forced to watch as his parents were killed and was poisoned by yin fen as a sort of revenge against all Carstairs. This man was the story that was passed down as a lesson to Downworlders (“don’t misbehave, they say there’s a Shadowhunter that defies death and helped defeat the clockwork army”) and to little Shadowhunters (“there’s a man that gave up his freedom to ensure his love and his _parabatai_ stayed alive”).

“Bitten or born?”

“B-born.” He was flinching under the blood red of Derek’s stare, molten gold fading to a stormy gray and teeth returning to blunt human ones. “I was born.” Derek studies him for a minute, taking in the brown of his complexion and the way his hands shook; his accent suggests an upbringing in Mexico and the tattoo inside his right wrist of a quote from the bible was written in Spanish but infected from a dirty needle.

“What happened to your pack?” Gold colors his eyes again and a vicious snarl makes Derek’s hackles rise, another warning growl putting the omega back in his place. There was a pack hierarchy for a reason and Derek would be damned if he allowed this omega to have visions of grandeur (he got enough of that from Peter until a bloodthirsty Alpha wandered into town and ended up buried in the Preserve).

“Calaveras swooped in and wiped them out during the War. Alicante wasn’t the only place that suffered.” Derek knew about that all too well, remembering the burning pain of Fae weapons that took forever to heal. “You know Araya?”

“All too well.”

“She and her brood came bursting into my family’s home claiming that they had proof that we’d sided with the Courts, that werewolves were filthy dogs brought even lower by the Fair Folk’s influence. She and two of her boys slaughtered my pack, babies and all. I want them dead!”

“But you ran off instead.” It wasn’t an accusation, Derek and Laura had done exactly like that and had come to regret it just seven years later. He and Peter got their revenge, though, and they got Cora back to make things all the sweeter. “Did you try to contact the Clave for reparations?” Javier lets out a hoarse laugh, relaxing slightly in Jem’s hold when he realized the Shadowhunter wasn’t going to kill him.

“There wasn’t time, not with the Cold Peace being arranged and the reconstruction of their precious Idris. By the time they even considered taking my request, my anchor was lying dead in my arms.” Tears make his gray eyes shine, crystals under the moonlight as they made tracks through the grime covering his cheeks. “My daughter was only three years old and she died of a fever. _She was human_.”

“I understand.”

 _“How could you ever understand?_ ”

“I’m a Hale.” Javier goes stock-still, gaze turning a mix of wary and interested as he took in one half of the two Alphas that had wreaked havoc on a rogue family of Shadowhunters. Derek knew well what the tales had described, two wolves half out of their minds and storming the California Institute to rip out the throats of Gerard and Kate. The truth was far less dramatic (well, as less dramatic as things could be with Peter making the plans), they had lured the Argents to the old Hale house and killed them there. “I understand how you feel all too keenly.”

“You made a new pack?”

“Of a sort.” Derek manages a sad smile as he thinks about the pups that had joined him, the four Betas and the walking gecko (Jackson was forever angry that Stiles had taken to calling him Geico whenever he and Peter stopped in for a visit), not to mention a banshee with enough sass to put Alphas in their place beneath her Christian Louboutin heels. “Think you’ve calmed down enough for a hot meal and some tea?”

“You’d feed me after what I’ve done?”

“You roughed me up a little, nothing I couldn’t handle. Jem, you wanna…?” Jem shrugs and releases the ‘wolf, taking a few steps back. “Come on, it just so happens I know the owners of this shop.” Derek leads the way into _Sparks and Lightening_ , nodding at Stiles as they all file inside. “Where’s Peter?”

“I sent him out for pizza. Figured you’d want some carbs after getting your ass handed to you.” Javier snorts, looking over at the warlock with something like reverence. Whether it was because Stiles spoke to an Alpha so casually or because the man was beautiful, Derek would probably never know. “You two hungry back there?”

“Starving,” Javier nods, rubbing at his belly through the tattered blue shirt. “I haven’t eaten anything warm in months.”

“You’re not the type to hunt?”

“No, I’ve been a vegetarian for two years now. My daughter, she was always getting upset at the thought of eating helpless animals and converted my entire… Pack.” His voice breaks and he nearly jumps out of his skin when Derek squeezes his shoulder. Once he realized the gesture wasn’t threatening, he melts into the touch, probably just as starved for it as he was a meal.

“Don’t worry,” Derek promises,” you’re pack now.”

***

Javier fit into the pack nicely, though he preferred California to the hustle and bustle of New York. He texted a near constant commentary to Lydia about the drama of Beacon Hills, everything from the Kelpie attacks to the prank war Stiles and Allison had launched against Chris that only ended when they were all drenched in neon green paint and Javier reigned victorious.

By the time he’d been in the pack for three months, he had put on some weight and looked a lot healthier, though that was mostly because of regular therapy sessions with the local druids. It didn’t hurt that Araya Calavera and her two boys were killed in a freak accident just on the border of California, their throats slashed and their eyes burned right out of their skulls. And if Javier and Stiles just so happened to be in the area at the time, well the Clave didn’t need to know.

Javier was a hard worker and smarter than most people Derek had ever met before, spending all his free time curled up in the bookstore with some novel or another propped up on his knees (he and Lydia talked about math theories for ages one Christmas and only stopped when Jace threatened to bludgeon them with his stele). It wasn’t a surprise for any of them that the ‘wolf was accepted for a teaching position at BHHS as the new science teacher. No one mentioned that teachers didn’t tend to last long and all were surprised when he came home one night and revealed that his newest friend was the half-mad lacrosse coach with the hair that defied gravity.

By the end of his fifth year in Beacon Hills, he sent Lydia a picture of a pretty woman with blue-green hair and a beautiful pair of brown eyes. She was a mermaid that had come to California on vacation, hailing from somewhere in the Mediterranean with an accent that depended on her mood.

***

Apparently mermaids were even better pranksters than all the Downworlders in Beacon Hills because the next prank war is won by Theodosia when she used her low grade Siren Call to get the others to do the Macarena in front of half the town. Derek has the video on his phone to prove it and he’d make sure it got passed down for generations to come.

***

It’s nearly three in the morning when Derek wakes up to his cell phone ringing, his hand knocking pretty much everything off his nightstand when he tried to answer the fucking thing. “What,” he snaps down the line when he finally manages. What Peter tells him a second later is enough to have him sitting bolt upright in bed with sleep the last thing on his mind. “What the fuck do you mean you and Stiles knocked up the mermaid?” There’s a muted thump down the hall and then Lydia is panting in the doorway, Jackson stumbling in behind her with his blond hair sticking up all over the place.

“You tell Peter that this had better be a joke or I’m going to murder him slow,” she demands, eyes narrowed into a glare that could make Deucalion tuck tail and run.

“Did you get that?” There’s arguing on Peter’s end, then a yelp, and then it’s Stiles talking to him while his uncle whined on the floor. “Oh, well I guess that’s not so bad.” Derek turns his gaze back to Lydia, keeping his eyes locked on her face since she was currently glowering away in her birthday suit. “Theo’s a surrogate for them, you don’t have to kill anyone.”

“Who the fuck would willingly let Peter raise a baby,” Jackson asks. And yeah, that’s a pretty legitimate question considering Peter couldn’t even keep a plant alive pre-Stiles.

“Stiles says to shut up or he’ll dose your drink next time you come down and shave you bald.”

“I’d like to see him try.”

“He also says something about a picture from junior year and Nair in your shamp—”

“I fucking knew that was him!” Jackson’s face would probably be beet red if not for the green scales appearing, blue eyes flashing brightly in the dark hallway as he turns to look at his girlfriend. “I told everyone, but nobody believed me!”

“Now he says to go sale someone car insurance, so he can have a sensible conversation with me and Lydia.” There was also something in there about useless geckos and toxic masculinity, but Derek thought it was best to leave that out while Jackson pouted about bald spots that didn’t grow back right until he got the Bite.

***

Javier was just as excited as everyone else about the fact that Peter and Stiles would be having a baby of their very own. He didn’t want anymore kids of his own after having to bury his little girl, but that didn’t stop him from putting together a list of possible names from all nationalities, highlighting his favorites and debating meanings with Stiles during their lunch breaks.

Some of the teachers even got in on the name game, putting together a jar filled with their favorites and forcing Javier to deliver it on his way home (Finstock insisted that Bobby could easily be a girl’s name and that they shouldn’t shoot him down so quickly). By the time that Theodosia was actually showing, the entire town knew of her pregnancy and had already swarmed _Sparks and Lightening_ for all the baby books they had, which was redundant considering Stiles and Peter just put them back after they’d perused the more interesting ones.

The pack in New York weren’t much better; Lydia and Jackson bought out an entire baby boutique, Boyd and Erica offered up free babysitting anytime even if they had to portal to California to do it, Derek and Cora offered up the Hale family crib that had been in storage and was undamaged by the fire, and Isaac gave them a homemade book of lullabies that his father used to sing to him when he was little.

The Argents weren’t much different, deciding that they’d help to train the baby when it was old enough that way it stood a chance against the various monsters and demons that tended to pop up like clockwork. Stiles jumped on that opportunity and even phoned in a favor from Alec for some extra training where taking care of angry babies was concerned.

Of course, the biggest help was Javier during the nighttime cravings of peanut butter and Oreo blasts from Sonic. Armed with Peter’s MasterCard, he set out at all hours to make sure his girlfriend was never hungry even if it meant plugging his nose because the smell of French Onion Dip was foul enough to make him gag in the grocery store.

***

Pregnancy, Javier decided one day in early November, was still the worst thing to ever happen. Derek just so happened to agree with him since he’d made the mistake to come visit for a few days and ended up lumped with his Beta to fulfill any food orders and just trying to keep Theodosia comfortable as the pregnancy progressed.

California winters weren’t so bad compared to other places, but the dropping temperatures combined with the sixty-five degrees that Theodosia insisted on keeping the house were enough to have Derek questioning his life choices. Was being the honorary uncle (Scott McCall would have to pry that title out of his cold dead hands) really worth his unmentionables falling off due to frostbite?

As if that wasn’t bad enough, Theodosia got downright _mean_ sometimes. She nearly bit poor Javier’s head off one afternoon when he’d made the mistake of mentioning the fit of her clothes. In his defense, he’d only meant that her shirt was tucked into the back of her pants, but the mermaid had launched into a rant of epic proportions of just what this pregnancy was doing to her body and that Javi could get bent if he didn’t like his girlfriend being fat.

Javi, being the sensible man that he was, went out and bought a hundred dollars’ worth of Häagen-Dazs and action movies.

***

The day Theodosia’s water breaks in the middle of Walmart is also the day that Derek discovers just how truly useless his uncle-in-law is. The warlock puts two and two together about why the mermaid was currently leaking and then he fainted in the middle of the candy aisle.

They ended up leaving Stiles there until they had Theodosia checked into the hospital.

***

Alejandro Theodore Stilinski-Hale is born on December fifteenth, a whole five pounds that felt like nothing as Derek held him for the first time. The baby slept fitfully for the most part until a ‘wolf was holding him, soaking up their warmth and making soft sounds of contentment. Derek would deny crying if anyone asked, but the proof was Peter’s screensaver for nearly two months until little Alex smiles for the first time.

***

Javier and Theodosia officially move in together after dating for three years, adopting a little black cat to make it permanent. Neither of them understands why Derek and Stiles share a smile when Miguel is suggested as a possible name.

They end up naming it Coach to make Finstock stop complaining.

**Author's Note:**

> For anyone wondering, Javier’s tattoo is 1 Peter 5:7 “Cast all your anxiety on Him because He cares for you”.


End file.
